1. Field of the Invention
The present invention relates to a control device integrated dynamo-electric machine to be used on a vehicle or the like and, more specifically, to a control device integrated dynamo-electric machine including an inverter bridge having a plurality of semiconductor switching elements and a heat sink for cooling the semiconductor switching elements provided on the dynamo-electric machine.
2. Description of the Related Art
Recent years, hybrid cars start to appear in view of problems of global warming and resource saving. The hybrid car has a system including a power unit having an engine and a motor combined to each other, and has an idling-stop function to stop engine when the vehicle stops at a red light and, when the light is turned green, restart the engine automatically and quickly with the motor by determining the change of the light from the operation of a brake and an accelerator by a driver, a function to assist acceleration when accelerating the vehicle by the motor according to the state of acceleration to alleviate a load applied to the engine, which is an internal combustion engine. However, this system requires a high-voltage battery and a high-output motor, and hence the system itself costs much.
In contrast, in order to aim the system to be generally familiarized, a system limited to an idling-stop-specific function for reducing the cost is now in development.
As such a system, an inverter-integrated AC motor as disclosed in, for example, JP-A-2004-274992 (see description, FIG. 1 and FIG. 3) is proposed. This system includes an inverter function integrated in an alternator in the related art as a structure, that is, a motor function for starting the engine is added to a power-generating function of the alternator in the related art.
FIG. 10 is a schematic circuit diagram of the control device integrated dynamo-electric machine in the related art showing a relation of connection among a control device provided with a power device unit having an inverter, a dynamo-electric machine, a battery, and so on.
In FIG. 10, a dynamo-electric machine 1 includes an armature winding 16a wound around a stator and a field winding 14 wound around a rotor, and the armature winding 16a is configured by connecting coils of three phases (U-phase, V-phase, and W-phase) into a Y-connection (Star-connection).
A power device unit 4 includes an inverter bridge 40, which is referred to as an inverter module, having a plurality of switching devices (power transistor, MOSFET, IGBT, etc.) 41 as power devices and diodes 42 arranged in parallel with the respective switching devices 41, and a capacitor 43 connected to the inverter bridge 40 in parallel.
The inverter bridge 40 includes three modules, each module including two sets of a switching device 41a and the diode 42 which constitute an upper arm (high-potential arm) 46 and the switching device 41b and the diode 42 which constitute a lower arm (low-potential arm) 47 arranged in series, and the three modules are arranged in parallel corresponding to three phases (U-phase, V-phase and W-phase).
Ends of the respective phases of the Y-connection of the armature winging 16a are electrically connected to midpoints between the switching device 41a of the upper arm 46 and the switching device 41b of the lower arm 47 respectively in the respective phases U, V and W via AC wirings 9.
A positive terminal and a negative terminal of a battery 5 are electrically connected to a positive side and a negative side of the inverter bridge 40 respectively via DC wirings 8. In the inverter bridge 40, the switching operation of the respective switching devices 41a, 41b are controlled by a command from a control circuit 44. The control circuit 44 controls a field current control circuit 45 to adjust a field current to be supplied to the field winding 14 of the rotor.
In the dynamo-electric machine 1 provided with the power device unit 4 as described above, a DC power is distributed from the battery 5 to the power device unit 4 via the DC wirings 8 when the engine is started. Then, the control circuit 44 turns ON and OFF the respective switching devices 41a, 41b of the inverter bridge 40, so that the DC power is converted to a three-phase AC power. Then, the three-phase AC power is supplied to the armature winding 16a of the dynamo-electric machine 1 via the AC wirings 9. Accordingly, a revolving magnetic field is provided in the periphery of the field winding 14 of the rotor being supplied with the field current by the field current control circuit 45, and hence the rotor of the dynamo-electric machine 1 is driven to rotate, whereby the engine is started via a dynamo-electric machine pulley, a belt, a crank pulley, and a clutch (ON).
On the other hand, when the engine is started, the revolving power of the engine is transmitted to the dynamo-electric machine 1 via the crank pulley, the belt, and the dynamo-electric machine pulley. Accordingly, the rotor of the dynamo-electric machine 1 is driven to rotate, and a three-phase AC voltage is induced in the armature winding 16a. Therefore, the control circuit 44 turns ON and OFF the respective switching devices 41 to convert the three-phase AC power induced in the armature winding 16a into the DC power, thereby charging the battery 5.
In the dynamo-electric machine in the related art, the arms in the three-phase circuit which constitute a power unit of the control circuit each include a single semi conductor switching device. Although it depends on the generated current to be used continuously required for a power generator for vehicles and the requirement of an engine torque, it is necessary to supply a current which is at least 1.5 to 2 times the generated current for a short time for starting the engine. Since there is provided only one switching device, there is no flexibility in design according to power generation of the dynamo-electric machine, the current used when being driven, temporal conditions, cooling properties of the dynamo-electric machine, or the configuration of the heat sink, wiring members and so on. Consequently, it is obliged to use the switching device having a useless capacity or a size in terms of design.
Since there is no flexibility in design, if the priority is given to one of the power generation and the driving, it is obliged to reduce the current when the other one is in operation, and hence it becomes hindrance to achievement of high-power.
Since there is only one switching device, the malfunction of the device is directly led to the malfunction of operation of the dynamo-electric machine. Therefore, there remains a problem to be solved in reliability of the dynamo-electric machine.
In addition, there are generally small numbers of alternatives for the discrete multi-purpose devices having a capability of accommodating the current required for the dynamo-electric machine for vehicles as described above by itself. Therefore, it is necessary to develop a new switching device. However, development of the new switching device disadvantageously results in cost increase.
When it is mounted to vehicles such as automotive vehicles, it is also necessary to cope with constraint conditions such as downsizing and weight reduction.